Many modern integrated circuits utilize both bipolar and MOSFET (e.g. CMOS, NMOS, or PMOS) devices on a single chip. Such integrated circuits (when they combine bipolar and CMOS) are often termed "BiCMOS". Fabrication of BiCMOS (or even BiNMOS or BiPMOS) integrated circuits poses special problems for the process designer because certain process steps (e.g., heating, deposition, etching, etc.) which may facilitate the formation of, for example, improved bipolar devices, may adversely effect the formation of effective MOS devices.
Those concerned with the development of integrated circuit technology have consistently sought improved methods of integrated circuit fabrication.